Scanner module and image scanning apparatus employing the same

ABSTRACT

A scanner module and an image scanning apparatus employ an illuminator that includes at least one light emitting diode, a light guide to change the direction of the light from the light emitting diode, and a light source holder to which the light emitting diode is mounted, the light source holder being positioned in relation to the light guide such that the light source holder covers an incidence face of the light guide, on which the light from the light source is incident, the surface of light source holder facing the incidence face reflecting light incident thereupon. The reflection of light by the light source holder reduces the possibility of leakage of light, and can enhance luminous intensity of light of the illuminator.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of prior application Ser. No.12/183,691, filed on Jul. 31, 2008, now U.S. Pat. No. 7,954,988 whichclaims the benefit of Korean Patent Application No. 2007-0076640, filedon Jul. 31, 2007, and Korean Patent Application No. 10-2008-0065048filed on Jul. 4, 2008, and under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 12/118,856 filed on May 12, 2008, the disclosure ofeach of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scanner module and an image scanningapparatus employing the scanner module, and, more particularly, to amounting structure of a light guide in a scanner module.

2. Description of the Related Art

Generally, a scanner module may be employed in an image readingapparatus to read image from a desired portion of a document. To thisend, a scanner module may include an illuminator to irradiate light tothe portion of the document to be read and a focusing lens to focus thelight reflected from the portion of the document on an image sensor.

With recent development of inexpensive high-luminous-intensity whitelight emitting diodes, a scanner module employing white light emittingdiodes as the light source has been developed.

An illuminator however also needs to have an appropriate lightdistribution to provide a uniform image output for each pixel. For thisreason, a light guide has been used to guide light, irradiated fromlight emitting diodes, to the desired illuminating position.

An example of an illuminator that employs light emitting diodes and alight guide, is disclosed in U.S. Pat. No. 6,357,903 B1 to Furusawa etal. (“Furusawa”), which was issued on Mar. 19, 2002).

In legacy illuminators, e.g., one described by Furusawa, a light sourceis provided at one end of an elongated transparent light guide that ismounted in a case by being slid lengthwise into the case. During thelengthwise insertion onto the case, damages to the light guide suffer,e.g., scratches, or the like, which may have adverse effect on thescanning performance. In addition, there is no structure to guide thelight guide into the proper mounting position, exacerbating thepossibility of damages, and resulting in imprecise assembly.

When light emitting diodes are used as the light source of anilluminator, the luminous intensity may be limited to a predeterminedlevel. While a higher current or voltage is supplied to the lightemitting diodes may result in the light emitting diodes producing lightwith enhanced luminous intensity, the increased power also raises thetemperature of the light emitting diodes, and, consequently, maydeteriorate the luminous intensity of light actually emitted by thelight emitting diodes.

Moreover, it is desirable that an illuminator be easy to assemble so asto allow mass production. A conventional light guide is formed as anelongated transparent member, which is prone to bending or bowing. It isthus also desirable to provide a guide holder that is capable ofsupporting the light guide while maintaining the light guide straight.

Furthermore, in the above-described conventional illuminator, both endsof the light guide are fixedly supported, causing the light guide tobend or bow along its length when the light guide lengthens due tothermal expansion by heat generated from the light source. Thesedeformation or damages, e.g., bending or scratches, or the like, of thelight guide causes variation in characteristics of light, and adverselyaffects the scanning performance and/or quality.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and advantages of the embodiments of the invention willbecome apparent and be more readily appreciated from the followingdescription of the embodiments, taken in conjunction with theaccompanying drawings, of which:

FIG. 1 is a sectional view illustrating optical arrangement of a scannermodule in accordance with an embodiment of the present invention;

FIG. 2 is a perspective view of the scanner module in accordance with anembodiment of the present invention;

FIG. 3 is an exploded perspective view illustrating an illuminator inaccordance with a first embodiment of the present invention;

FIG. 4 is a perspective and partial sectional view of portions of theilluminator of FIG. 3;

FIG. 5 is a sectional view of the illuminator of FIG. 3;

FIG. 6 is a perspective view illustrating an embodiment of a lightsource holder of the illuminator of FIG. 3;

FIG. 7 is a sectional view of the portion “A” of FIG. 6;

FIG. 8 is a partial sectional view illustrating coupling of a guideholder and light source holder shown in FIGS. 2-7

FIG. 9 is a block diagram illustrating an image scanning apparatusemploying a scanner module in accordance with an embodiment of thepresent invention;

FIG. 10 is a perspective and a partial sectional view of an illuminatorin accordance with a second embodiment of the present invention;

FIG. 11 is an exploded and a partial sectional view of relevant portionsof an illuminator in accordance with a third embodiment of the presentinvention;

FIG. 12 is an exploded perspective view illustrating a scanner moduleincluding an illuminator in accordance with a fourth embodiment of thepresent invention;

FIG. 13 is a plan view illustrating coupling of a light source and lightsource holder provided in the scanner module shown in FIG. 12;

FIG. 14 is a view illustrating numerical analysis results of deformationof a light guide in response to thermal expansion of the light guidewhen no elastic member is provided;

FIG. 15 is a view illustrating numerical analysis results of deformationof a light guide in response to thermal expansion of the light guidewhen elastic members are provided;

FIG. 16 is a graph comparing temperatures of a light source in bothcases where the light source is elastically supported by metal elasticmembers and where no elastic member is provided;

FIG. 17 is a sectional view illustrating an embodiment of the mountingof the light guide mounted in an illuminator;

FIG. 18 is a view illustrating numerical analysis results of deformationof a light guide in response to thermal expansion of the light guidewhen no supporting protrusion is provided;

FIG. 19 is a view illustrating numerical analysis results of deformationof a light guide in response to thermal expansion of the light guidewhen supporting protrusions are provided; and

FIG. 20 is an exploded perspective view illustrating a scanner moduleincluding an illuminator in accordance with a fifth embodiment of thepresent invention.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. While the embodiments are described with detailedconstruction and elements to assist in a comprehensive understanding ofthe various applications and advantages of the embodiments, it should beapparent however that the embodiments can be carried out without thosespecifically detailed particulars. Also, well-known functions orconstructions will not be described in detail so as to avoid obscuringthe description with unnecessary detail.

FIG. 1 is a sectional view illustrating optical arrangement of a scannermodule 10 according to an embodiment of the present invention. Referringto FIG. 1, the scanner module 10 may be devised to scan an image acrossa sub scanning direction X. The scanner module 10 includes anilluminator 110, which irradiates a light to a document platform D, afocusing lens 120, which focuses the light reflected from a scan objectP, such as a document, or the like, disposed on the document platform D,and a sensor unit 130, which receives the light focused by the focusinglens 120 and senses an image based on the received light. The scannermodule 10 further includes a scanner module body 100 having an innerspace in which the focusing lens 120 and the sensor unit 130 may behoused. A seating recess 100 a (See FIG. 2) may provided on the topportion of the scanner module body 100 for accommodating the illuminator110.

The illuminator 110 serves to irradiate light to the scan object P. Asshown in FIGS. 2 and 3, the illuminator 110 may include light source ofsources 111 that produce the light, and light source holders 112 towhich the light sources 111 are mounted. The illuminator 110 may furtherinclude light guides 113, the lengths of which extend along a mainscanning direction Y (orthogonal to the sub scanning direction X), andwhich are arranged to face and oppose the document platform D. Theilluminator 110 may further include a guide holder 114 having lightguide mounting portions 114 a for mounting of the light guides 113 andlight source mounting portions 114 b for mounting of the light sourceholders 112.

Referring again to FIG. 1, the focusing lens 120 is located between thedocument platform D and the sensor unit 130, and serves to focus thelight reflected from the scan object P onto the sensor unit 130.

The sensor unit 130 receives the light focused thereon by the focusinglens 120, and serves to detect an image of the scan object P based onthe received light. Depending on the particular scanning application,the sensor unit 130 may have a single-row configuration, or a multiplerow configuration, for scanning of Red/Green/Blue color images orRed/Green/Blue/Black-and-White images. Specifically, the sensor unit 130may include image sensors, e.g., charge coupled device (CCD) orcomplimentary metal oxide (CMOS) pixel elements, for respective colors,which are arranged in plural rows spaced apart from one another.

A plurality of reflecting mirrors 140 may further be provided betweenthe scan object P and the focusing lens 120. The reflecting mirrors 140serve to define a light path within the inner space of the scannermodule body 100. To this end, the reflecting mirrors 140 reflect thelight reflected from the scan object P, and change the light path todirect the light toward the focusing lens 120. Providing the pluralityof reflecting mirrors 140 may advantageously achieve the required lightfocusing distance between the scan object P and the sensor unit 130, andmay also result in a compact size of the scanner module body 100. In thepresent embodiment, the scanner module 10 is provided with fourreflecting mirrors 140, but the present invention is not so limited, andany number of reflecting mirrors can be selected for a particulardesign.

FIGS. 2 to 5 are a perspective view, an exploded perspective view, apartial perspective view, and a sectional view, respectively,illustrating the illuminator employed according to the first embodimentof the present invention. FIG. 6 is a perspective view illustrating thelight source holder according to an embodiment. FIG. 8 is a partialsectional view illustrating assembly of the guide holder and the lightsource holder shown in FIGS. 2-6.

Referring to the drawings, the illuminator 110 is employed in thescanner module 10, to irradiate light to the scan object P, which isdisposed on the document platform D, in the main scanning direction Ythat is substantially orthogonal to the sub scanning direction X of thescanner module 10.

The illuminator 110 includes light sources 111 producing light, thelight source holders 112 to which the light sources 111 are mounted, thelight guides 113 longitudinally arranged along the main scanningdirection Y to face the document platform D, and the guide holder 114,in which the light guides 113 are mounted.

Each of the light sources 111 may include a substrate 111 a mounted tothe light source holder 112, and light emitting diodes 111 b formed onthe substrate 111 a to irradiate light upon receiving power through thesubstrate 111 a. In an embodiment, the light emitting diodes 111 b maybe white light emitting diodes.

The light guides 113 change a direction of the light irradiated from thelight sources 111, so as to direct the light to an image reading regionon the document platform D. In one embodiment, to enhance the luminousintensity of light to be directed to the image reading region, theplurality of light guides 113 may be provided.

The light guides 113 are made of a transparent material such as glass,plastic, or the like, and have an elongated shape, the length of whichextending along the main scanning direction Y. Each of the light guides113 includes at least one incidence face 113 a, guide faces 113 b and anemission face 113 c.

The incidence face 113 a receives the light from the corresponding lightemitting diode 111 b. The incidence face 113 a is formed on at least oneof both longitudinal ends of the respective light guides 113. Here, thelight source 111 is mounted to the light source holder 112 such that thelight source 111 faces the incidence face 113 a of the light guide 113.

The emission face 113 c opposes the document platform D, through whichthe light diffused and reflected by the guide faces 113 b is emitted. Inone embodiment, the emission face 113 c may form a collimating lens.

The guide faces 113 b are formed at both longitudinal sides of the lightguide 113. If light is introduced through the incidence face 113 a viatotal internal reflection, the guide faces 113 b guide the direction ofthe light, allowing the light to be emitted throughout the emission face113 c.

The reflecting face 113 d reflects the light, introduced thereto throughthe incidence face 113 a, toward the emission face 113 c. The reflectingface 113 d is formed at the light guide 113 at an opposite side of theemission face 113 c. For reflection of light, the reflecting face 113 dhas a light reflecting pattern defined by convex and concave portions.

In the present embodiment, a pair of the light guides 113 is arranged tobe adjacent to each other along the sub scanning direction X. The pairof light guides 113 may be tilted towards each other to direct the lightto the image reading region without interfering with the light reflectedfrom the scan object P. That is, as shown in FIG. 1, center axes C1 andC2 of light having passed through the two respective light guides 113are tilted with respect to the center optical axis Z.

In the embodiment shown, a pair of the light sources 111 is provided foreach of the light guides 113, a pair of the light emitting diodes 111 bbeing installed on the substrate 111 a of each light source 111. Withthis configuration, the two light emitting diodes 111 b of each of thepair of light sources 111 can irradiate the light on each incidence face113 a formed at both ends of each of the pair of light guides 113.

In addition, a light source holders 112 is provided on each longitudinalends of the guide holder 114 such that a light source 111 is provided oneach of the ends of each light guide 113. When light is irradiated fromthe light source 111 provided at one end of a light guide 113, and isintroduced to the light guides 113 through the incidence faces 113 afacing the light source 111, in order to prevent the light from leakingfrom the light guides 113 through the incidence faces 113 a at the otherend, the pair of light source holders 112 are arranged to cover bothincidence faces 113 a of the respective light guides 113, the lightsource holders 112 being adapted to reflect the light. That is, the pairof light source holders 112 covers the pair of incidence faces 113 a ofeach light guide 113, thereby preventing the light, introduced into thelight guide 113 through the incidence faces 113 a of on one end, fromleaking from the light guide 113 through the incidence face 113 a on theother end of the light guide 113.

In an embodiment, preferably, the light source holders 112 are made of awhite material to reflect and diffuse light, the material having a lightreflectivity of 70% or greater. With adoption of the light sourceholders 112 to prevent the light, irradiated from the light sources 111into the light guides 113, from leaking from the light guides 113through the incidence faces 113 a, the illuminator 110 can achievegreater luminous intensity of light using the same light sources 111.

While the above embodiment is described to include a pair of lightsources 111 at each end of the light guides 113 via the pair of lightsource holders 112, but this configuration is given only as an example.Alternatively, a single light source 111 may be mounted to only one endof each of the light guides 113 via a single light source holder 112.

According to an embodiment, the guide holder 114 may serve to guidemounting positions of the light guides 113 and the light sources 111. Tothis end, the guide holder 114 is formed with at least one light sourcemounting portion 114 b to which the light source holder 112 may bemounted to provide a light source 111 on at least one end of each of thelight guides 113, and the light guide mounting portions 114 a in whichthe light guides 113 are to be mounted.

Each light guide mounting portion 114 a may be recessed into the guideholder 114 extending longitudinally along the main scanning direction Y,and has a shape corresponding to that of the light guide 113. Forexample, in the embodiment shown, the light guide mounting portion 114 amay have a trapezoidal cross-sectional shape having an inwardly taperedcross section. In the embodiment, the pair of the light guide mountingportions 114 a are arranged adjacent each other along the sub scanningdirection X, and extend parallel to each other along the main scanningdirection Y such that the pair of light guides 113 can be mountedparallel to each other.

Preferably, the light guide 113 is inserted into the light guidemounting portion 114 a by being moved in a direction orthogonal to thelongitudinal direction of the light guide 113. If the light guide 113 isinserted into the longitudinal direction of the light guide mountingportion 114 a, scratches may occur on an outer surface of the lightguide 113. Inserting the light guide 113 in a direction orthogonal tothe longitudinal direction thereof may reduce the possibility ofscratching the light guides 113. For example, in the embodiment shown,the light guide mounting portion 114 a has, e.g., a trapezoidal crosssection with its height significantly smaller than its length.Therefore, when a light guide 113 is inserted into the light guidemounting portion 114 a along the height of the light guide mountingportion 114 a, i.e. orthogonal to the longitudinal direction of thelight guide 113, the contact distance between the light guide 113 andthe light guide mounting portion 114 a may be substantially shorter thatwhen the light guide 113 is received into the recess in lengthwisedirection, and. consequently, damage to the light guide 113 can beminimized.

The guide holder 114 may be made of a flexible material, which iselastically deformable in response to a pressing force. For example,before the light guide 113 is inserted into the light guide mountingportion 114 a, the light guide mounting portion 114 a, as represented bythe dotted line in FIG. 5, may have a narrower initial inner space thanthe space required for mounting of the light guide 113.

When the light guide 113 is received into the light guide mountingportion 114 a, as shown in FIG. 5, the light guide mounting portion 114a expands by the insertion of the light guide 113, preventing unwantedmovement of the light guide 113 after installation.

According to an embodiment, the illuminator 110 may further includespacers 114 c provided on the inner surface of the light guide mountingportion 114 a to support the light guide 113.

Once the light guide 113 is inserted into the light guide mountingportion 114 a that includes the spacers 114 c, the light guide 113 canbe supported by the spacers 114 c while allowing gaps between the lightguide 113 and the inner surface of the light guide mounting portion 114a. Providing the spacers 114 c may further alleviate the problem ofincompletely supporting the light guide 113 due to spatial deformationof the light guide mounting portion 114 a resulting during manufactureof the guide holder 114. This consequently reduce bending of the lightguide 113, and helps to maintain straightness of the light guide 113.

A plurality of spacers 114 c may be spaced apart from one another alongthe longitudinal direction of the light guide 113. For example, in thepresent embodiment, the spacers 114 c may be provided at the center andat opposite ends of the light guide mounting portion 114 a along itslength. As shown in FIG. 5, the spacers 114 c may be arranged on theside wall surfaces and bottom surface of the light guide mountingportion 114 a, so as to support the light guide 113 in three directions.

When a pair of the spacers 114 c are arranged on the side wall surfacesof the light guide mounting portion 114 a, the distance between thespacers 114 c on opposite wall surfaces may be made smaller than thewidth of the light guide 113 to be located between the spacers 114 c.With this configuration, as the light guide 113 is inserted into thelight guide mounting portion 114 a, the guide holder 114 is elasticallydeformed to provide a required installation space for the light guide113, and the light guide 113 can come into pressing contact with therespective spacers 114 c. In one embodiment, the spacers 114 c may beformed integrally with the guide holder 114, which may improve assemblyefficiency, and may reduce manufacturing costs.

The light source holder 112 may include a fixing portion 112 a to keepthe light guide 113 in place. The fixing portion 112 a protrudes to havean inner contour corresponding to the contour of the emission face 113 cof the light guide 113, and can be made to come into direct or indirectcontact with the emission face 113 c of the light guide 113 so as toprevent vertical movement of the light guide 113.

For example, as shown in FIG. 6, the light source holder 112 may furtherinclude a fixing rib 112 b formed on the inner edge surface of thefixing portion 112 a. Once the light guide 113 is mounted in the lightguide mounting portion 114 a, the fixing rib 112 b may come into partialcontact with the light guide 113, and can keep the light guide 113 inposition.

During the coupling of the light source holder 112 to the guide holder114, the fixing rib 112 b and the light guide 113 move relatively eachother while being in contact, possibly causing the light guide 113 to bescratched. Thus, in one embodiment, the fixing rib 112 b may be taperedas shown in FIG. 7. The tapered fixing rib 112 b may reduce possibledamages to the light guide 113 during the installation of the lightsource holder 112 in the guide holder 114.

To address the possible thermal expansion of the light guide 113,according to an embodiment shown in FIG. 7, the fixing rib 112 b may beprovided with a neck portion 112 c, which forms a recessed portionbetween the fixing portion 112 a and the fixing rib 112 b.

If a greater pressure is applied to an outer surface of the fixing rib112 b as the light guide 113 is thermally deformed, the neck portion 112c allows elastic movement of the fixing rib 112 b. As a result, thelight guide 113 can be stably supported at a fixed position withoutdamaging the fixing rib 112 b. The structure of the neck portion 112 cis described only by way of an example for addressing thermaldeformation of the light guide 113, and does not limited the presentembodiments to the particular structure. Various other shapes orstructures can also be employed to account for the thermal expansion ofthe light guide 113. For example, when the light source holder 112, thefixing portion 112 a and/or the fixing rib 112 b itself is made of anelastically deformable flexible material, the light source holder 112can also stably support the light guide 113.

In addition, the illuminator 110 may further include positioning guides112 d and 114 d to set the mounting position of the light source holder112 relative to the guide holder 114. The positioning guides 112 d and114 d are shaped to match each other, and are arranged to be opposingpositions on the guide holder 114 and the light source holder 112,respectively. When coupling the light source holder 112 to the guideholder 114, the coupling position can be set on the basis of thepositioning guides 112 d and 114 d, making rapid and accurate couplingbetween the guide holder 114 and the light source holder 112 possible.

Preferably, the light source holder 112 may be capable of beingsnap-fitted to the mounting portion 114 b of the guide holder 114.Snap-fitting may not require any screws or bonding adhesives and,therefore, advantageously enables easy coupling.

The light source holder 112, as shown in FIG. 3, can be coupled to themounting portion 114 b in a direction substantially parallel thelongitudinal direction of the light guide 113. To that end, to mount thelight source holder 112 in the mounting portion 114 b, hook members 112e and holding protrusions 114 e may be provided.

The hook members 112 e, as shown in FIGS. 6 and 8, may extend from asurface of the light source holder 112 facing the guide holder 114, andthe holding protrusions 114 e may be provided at positions of the guideholder 114 corresponding to the mounted positions of the respective hookmembers 112 e. When the hook members 112 e engage the holdingprotrusions 114 e, the light source holder 112 may be coupled to theguide holder 114.

While in the above embodiment, the light guide holder 112 is describedto have formed therewith the hook members 112 e, and the guide holder114 as including the holding protrusions 114 e, but the presentinvention is not so limited. For example, the respective locations ofthe hook members and holding protrusions may be reversed.

In addition, the hook members 112 e are not limited to theabove-described configuration. For example, according to a secondembodiment of illuminator shown in FIG. 10, each hook member 212 e ofthe light source holder 212 may be formed, at the distal tip endthereof, with a relatively large width portion while the light sourcemounting portion 214 b of a guide holder 214 may be provided with arecess having a shape corresponding to that of the hook member 212 e.Accordingly, the light source holder 212 can be coupled to the guideholder 214 as the hook member 212 e is snap-fitted in the mountingportion 214 b as shown in FIG. 10.

Referring to FIG. 11 illustrating an illuminator according to a thirdembodiment, a light source holder 312 may be fitted into a mountingportion 314 b of a guide holder 314 in a direction orthogonal to thelongitudinal direction of a light guide 313. For example, an illuminatorof this embodiment may further include hook members 312 e and holdingprotrusions 314 e, to stably fit the light source holder 312 into themounting portion 314 b.

The hook members 312 e, as shown in FIG. 11, may protrude downward fromside edges of the light source holder 312, and the holding protrusions314 e may be provided at positions of the guide holder 314 correspondingto the mounted position of the respective hook members 312 e.Accordingly, as the hook members 312 e engage the holding protrusions314 e, the light source holder 312 can be coupled to the guide holder314.

When the light source holder 312 is coupled to the guide holder 314 inthe above-described direction, as there is substantially no risk of thecontact position between the fixing rib of the light source holder 312and the light guide 313 being changed during assembly, the generation ofscratches can thus be substantially avoided.

The above-described configuration of the illuminator, along with one ormore features of previously described embodiments, advantageous allowsprecise positioning an/or quick coupling of the light guide 313 and thelight source 311. In addition, the light guide 313 can be firmlysupported to maintain straightness thereof.

Although the illuminator 110 in accordance with the first embodiment ofthe present invention includes the guide holder 114 to be mounted intothe scanner module body 100 after the light guides 113, light sources111 and light holders 112 are mounted to the guide holder 114, thepresent invention is not so limited. For example, referring to FIG. 12illustrating an illuminator according to a fourth embodiment, instead ofusing the guide holder 114, an illuminator 410 of a scanner module 40includes light guides 413, light sources 411 and light source holders412, and a scanner module body 400, on which the light guide mountingportions 400 a for mounting of the light guides 413 and the light sourcemounting portions 400 b for mounting of both the light sources 411 andthe light source holders 412 are provided. With this configuration, thelight guides 413, light sources 411 and light source holders 412 can bedirectly mounted into the scanner module body 400.

The light guide mounting portions 400 a extend along the main scanningdirection Y, i.e. in the longitudinal direction of the light guides 413.The light source mounting portions 400 b are formed, at both ends of thelight guide mounting portions 400 a, to have a larger width than thewidth of the light guide mounting portions 400 a. In the presentembodiment, a pair of the light guides 413 are mounted in the scannermodule body 400 such that they are parallel to each other in the subscanning direction X, and for mounting of the pair of light guides 413,a pair of the light guide mounting portions 400 a are provided parallelto each other in the sub scanning direction X.

In this embodiment, a light guide 413 is mounted in the light guidemounting portion 400 a in such a manner that at least one of thelongitudinal ends thereof is elastically supported by an elastic member414. This serves to minimize deformation of the light guide 413 causedwhen the light guide 413 increases in length due to thermal expansion byheat generated from the light sources 411. If the light guide 413increases in length due to thermal expansion, the light guide 413 maybecome convexly deformed, or bowed, at the center of an emission face413 c, causing variation in characteristics of light emitted through thelight guide 413 and deterioration in image scanning performance.

By elastically supporting at least one of end of the light guide 413using the elastic member 414, even if the light guide 413 increases inlength due to thermal expansion, the elastic member 414 can partiallycompensate for the increase in the length of the light guide 413 viaelastic deformation thereof as shown in FIG. 13. This substantiallyreduces the emission face 413 c of the light guide 413 from being bentor bowed.

FIG. 14 is a view illustrating results of numerical analysis ofdeformation of the light guide 413 when both the ends of the light guide413 are fixedly supported, and FIG. 15 is a view illustrating results ofnumerical analysis of deformation of the light guide 413 when both endsof the light guide 413 are elastically supported by the elastic members414.

As can be seen from FIGS. 14 and 15, the light guide 413 has adeformation amount of about 0.021 mm when both the ends of the lightguide 413 are fixedly supported, whereas the light guide 413 has adeformation amount of 0.012 mm when both the ends of the light guide 413are elastically supported by the elastic members 414. Accordingly, inthis example, it can be appreciated that supporting both the ends of thelight guide 413 via the elastic members 414 may reduce the deformationamount of the light guide 413 to about half.

When the length of the light guide 413 varies according to heatgenerated from the light sources 411, an incidence face 413 a of thelight guide 413 may become spaced further apart from a correspondinglight emitting diode 411 b of the light source 411. In this case, lightloss may occur as the light irradiated from the light emitting diode 411b passes through air between the light emitting diode 411 b and theincidence face 413 a. Therefore, to minimize the light loss, it ispreferred that the incidence face 413 a provided at either end of thelight guide 413 come into close contact with the corresponding lightemitting diode 411 b of the light source 411.

In an embodiment, to maintain the proper distance between the incidencesurface 413 a and the light emitting diode 411 b, the light source 411is mounted to either end of the light guide 413 via the light sourceholder 412, and the elastic member 414 is provided between the lightsource 411 and a wall surface of the light source mounting portion 400 bto elastically support the light guide 413 indirectly by way of thelight source 411. When supporting the light guide 413 in this mannerusing the elastic member 414 with the light source 411 being interposedbetween the incidence surface 413 a and the elastic member 414, theelastic member 414 can reduce the possible bowing of the light guide413, and may also allow the light emitting diode 411 b of the lightsource 411 to maintain a sufficiently close proximity to thecorresponding incidence face 413 a of the light guide 413, resulting inreduction of light loss.

Referring again to FIG. 12, the elastic member 414 according to anembodiment may be a leaf spring. The elastic member 414 in the form of aleaf spring consists of a center elastic portion 414 a, which isconvexly raised to exhibit an elastic force so as to elastically supportthe light source holder 112, and supporting portions 414 b which aredefined at both sides of the elastic portion 414 a to allow the elasticmember 414 to be supported in the light source mounting portion 400 b.The elastic member 414 may be made of a material exhibiting high thermalconductivity, such as metallic material, to thus serve, in addition toproviding the elastic support, as a radiating member to radiate heatgenerated from the light source 411 away from the light source 411.

FIG. 16 is a graph showing the measured temperatures of the light source411 in both cases of when the metal elastic members 414 is used and whenit was not. In the graph of FIG. 16, the dotted curve represents thetemperature variation when the elastic member 414 was not used, and thesolid curve represents the temperature variation when the metal elasticmember 414 is used. As can be seen from the graph, in this example, theuse of the metal elastic member 414 can lower the temperature of thelight source 411 by approximately 17° C.

According to an embodiment, to more effectively restrict the emissionface 413 c of the light guide 413 from being deformed by heat generatedfrom the light sources 411, supporting protrusions 415 protrude from anentrance of the light guide mounting portion 400 a, so as to support apart of the emission face 413 c of the light guide 413.

Specifically, the supporting protrusions 415 are integrally formed withthe scanner module body 400. The plurality of supporting protrusions 415protrude in the sub scanning direction X and are spaced apart from oneanother in the main scanning direction Y. As shown in FIG. 17, when apart of the emission face 413 c of the light guide 413 is supported bythe supporting protrusions 415, the supporting protrusions 415 canrestrict deformation of the light guide 413 even if the light guide 413thermally expands due to heat generated from the light sources 411. Inthe present embodiment, the pair of light guide mounting portions 400 aare arranged parallel to each other in the sub scanning direction X, andeach supporting protrusion 415 protrudes in the sub scanning direction Xfrom one side of the light guide mounting portion 400 a so as to supporta part of the emission face 413 c of the light guide 413.

FIG. 18 is a view illustrating numerical analysis results of deformationof the light guide 413 when not using the supporting protrusion 415, andFIG. 19 is a view illustrating numerical analysis results of deformationof the light guide 413 when using three supporting protrusions 415.

As can be seen from FIGS. 18 and 19, in this example, the light guide413 has a deformation amount of about 0.021 mm when the supportingprotrusion 415 was not used, whereas the light guide 413 has adeformation amount of about 0.014 mm when the emission face 413 c of thelight guide 413 is supported by the supporting protrusions 415.Accordingly, it can be appreciated that use of the supportingprotrusions 415 can substantially reduce the deformation amount of thelight guide 413.

As described above, when the light guide 413 is elastically supported bythe elastic members 414 and/or when the emission face 413 c of the lightguide 413 is supported by the supporting protrusions 415, deformation ofthe light guide 413 can be reduced. Accordingly, to minimize deformationof the light guide 413, as described with relation to the presentembodiment, it is preferred that both the ends of the light guide 413 beelastically supported by the elastic members 414 and that the emissionface 413 c of the light guide 413 be supported by the plurality ofsupporting protrusions 415.

The supporting protrusions 415 provided at the entrance of the lightguide mounting portion 400 a as described above, further, have theeffect of preventing the light guide 413 from being separated from thelight guide mounting portion 400 a even when subjected to vibration orshock during, e.g., transportation of the scanner module 40 or of avariety of appliances in which the scanner module 40 is included.

As a result of performing a drop test from a height of 30 cm, simulatinga drop that may be experienced by the scanner module 40 duringtransport, under several conditions of different numbers of supportingprotrusions 415, the light guide 413 was separated from the light guidemounting portion 400 a when two supporting protrusions 415 wereprovided, but remained in the light guide mounting portion 400 a whenthree supporting protrusions 415 were provided. Accordingly, it ispreferable that three or more supporting protrusions 415 be formed toprotect against external vibration or shock, in order to prevent thelight guide 413 from being separated from the light guide mountingportion 400 a of the scanner module body 400.

Referring again to FIG. 12, a reflecting face 413 d provided at thelight guide 413 has a convex and concave pattern. With thisconfiguration, a part of the light, irradiated from the light emittingdiodes 411 b and introduced into the light guide 413, may leak from thereflecting face 413 d of the light guide 413 to the outside, causinglight loss. Therefore, a reflecting plate 418 is disposed at the rearside of the reflecting face 413 d of the light guide 413, to reflect thelight, leaked from the reflecting face 413 d to the outside of the lightguide 413, toward the reflecting face 413 d, so as to allow thereflected light to be again introduced into the light guide 413 throughthe reflecting face 413 d. In the present embodiment, a pair of lightguides 413 are provided and therefore, a pair of reflecting plates 418are provided such that the reflecting plates 418 are provided at therear side of the reflecting faces 413 d of the pair of light guides 413,respectively. A supporting piece 418 a is formed at one side of eachreflecting plate 418, to be supported on one side of the light guide413. Through the supporting piece 418 a, the reflecting plate 418 can bestably mounted in the corresponding light guide mounting portion 400 a.

While an embodiment is described above to include an elastic member 414,in the form of a metal leaf spring, to elastically supports the lightguide 413 and the light source 411, the present invention is not solimited. For example, an elastic member 514, made of an elastic resinmaterial such as rubber, may alternatively be used as shown in FIG. 20.

Referring to FIG. 20, the elastic resin member 514 may exhibit poorthermal conductivity, and may not be as effective in removing the heatgenerated by the light source 511. In an embodiment, a radiating member516, made of material that has a sufficiently high thermal conductivity,may be provided between the elastic member 514 and the light source 511.

One end of the radiating member 516 may be located between the elasticmember 514 and the light source 511 while the other end of the radiatingmember 516 extends out of a light source mounting portion 500 b, and ismounted to a portion of the scanner module body 500. The heat generatedfrom the light source 511 is transferred along the radiating member 516,and is radiated via heat exchange with air outside the light sourcemounting portion 500 b. As a result, heat generated from the lightsource 511 can be radiated.

In the above-described configuration, thermal conductivity between thelight source 511 and the radiating member 516 is proportional to thecontact area between the light source 511 and the radiating member 516.When facing surfaces of the light source 511 and the radiating member516 are not flat and thus, have a relatively small contact area betweenthem, a thermal coupling 517 may be provided between the light source511 and the radiating member 516 to enhance the transfer of heatgenerated from the light source 511 to the radiating member 516. Thethermal coupling 517 may be made of a material exhibiting high thermalconductivity, and may be configured to closely contact both facingsurfaces of the light source 511 and the radiating member 516. Thethermal coupling 517 can indirectly maximize the contact area betweenthe light source 511 and the radiating member 516, and, consequently,can allow heat generated from the light source 511 to be effectivelytransmitted to and radiated by the radiating member 516.

FIG. 9 is a block diagram illustrating an image scanning apparatusemploying a scanning module, various embodiments of which have beendescribed above. Referring to the drawing, the image scanning apparatusmay include the scanner module 10, and an image processor 20 to processan image obtained from the scanner module 10. Here, the image scanningapparatus in accordance with the present invention may include, e.g., aMulti-Functional Printer (MFP), a digital copier, a scanner, afacsimile, or the like.

The scanner module 10 is substantially identical to the embodimentsvariously described above, a detailed description of which need not berepeated. The image processor 20 may include at least one of a fileproducer 21 to produce an image file from an image obtained from thesensor unit 130 (FIG. 1) and an image former 22 to form an image on aprinting medium on the basis of the obtained image.

The file producer 21 may be, e.g., a controller that may also controloperations of various components of the image scanning apparatus,including, e.g., the scanner module. To this end, according to anembodiment, the controller may be, e.g., a microprocessor, amicrocontroller or the like, that includes a CPU to execute one or morecomputer instructions to implement the various control operations of thescanning apparatus, and may further include a memory device, e.g., aRandom Access Memory (RAM), Read-Only-Memory (ROM), a flesh memory, orthe like, to store the one or more computer instructions. The method inwhich the controller controls various components of an image scanningapparatus is similar to that of well-known image scanning apparatuses,detailed description thereof is thus unnecessary.

The image former 22 may include one or more of components of an imageforming apparatus, for example, of an electro-photographic printingapparatus, that includes, e.g., a printing medium feeding unit thatholds, picks up and feeds printing medium, an exposure unit for drawinga latent image using light on a photosensitive surface, a developingunit to develop the latent image with toner, a transfer unit to transferthe toner image onto the printing medium, a fixing unit to fuse thetoner image sufficiently permanently on the printing medium and adischarging unit for discharging a printing medium on which an image hasbeen fixed. As known to those skilled in the art, there are manyavailable and known other various image forming mechanisms.

While the above embodiments are generally described in references toexamples of a charge coupled device module (CCDM) type scanner module,in which a light source and a plurality of reflecting mirrors constitutea single module, the present invention is also applicable to other typesof scanning module, including, e.g., a Mirror Moving Type (MMT), inwhich a light source and a single reflecting mirror constitute onemodule and two reflecting mirrors constitute another module.

Although embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. An image forming apparatus comprising: a document bed; and a scanningmodule operable to scan a document placed on the document bed, thescanning module including an illuminator to illuminate light onto thedocument to be scanned and a sensor to detect the light reflected by thedocument, the illuminator including: a first light guide that receiveslight from a first light emitting diode and a second light guidereceives light from a second light emitting diode, each of the lightguides having an elongated shape with an incidence face formed on one oflongitudinal ends thereof to receive light, the light guide to change adirection of the light received through the incidence face; wherein eachof the light guides includes: a first guide face, a second guide face,an emission face provided between the first and second guide faces toemit light from the light guide to the document to be scanned, and areflecting face located opposite to the emission face to reflect lightreceived through the incidence face, each of the first and second guidefaces extends between the longitudinal ends of the light guide such thata first plane corresponding to the first guide face forms an acute anglewith a second plane corresponding to the second guide face, wherein thefirst light emitting diode is mounted to a first light source holderhaving a white material at least on a side surface facing the incidenceface of the first light guide, and the second light emitting diode ismounted to a second light source holder having a white material at leaston a side surface facing the incidence face of the second light guide.2. The image forming apparatus of claim 1, wherein a surface area of theemission face is greater than a surface area of the reflecting face. 3.The image forming apparatus of claim 1, wherein the light reflectivityof 70% or greater is obtained by a white material on the side surface ofeach of the light source holders facing the incidence face of therespective light guide.
 4. The image forming apparatus of claim 1,wherein the first light emitting diode is mounted to a first lightsource holder having a light reflectivity of 70% or greater at a sidesurface facing the incidence face of the first light guide, and thesecond light emitting diode is mounted to a second light source holderhaving a light reflectivity of 70% or greater at a side surface facingthe incidence face of the second light guide.
 5. The image formingapparatus of claim 1, wherein the first light guide and the second lightguide are slantingly arranged in a light guide holder such that a centerline of light illuminating by each of the light guide is angled withrespect to a horizontal plane of the document bed.